Common-tower double-circuit T-type power transmission line fault distance measurement method based on positive sequence current difference

Abstract

The invention relates to a common-tower double-circuit T-type power transmission line fault distance measurement method based on positive sequence current difference. The method is characterized in that firstly, a current transformer at a protection mounting portion is utilized to acquire each phase current data of three ends of a double-circuit T-type power transmission line system, and a positive sequence current component of a double-circuit line is solved through a symmetric component method; secondly, distance measurement functions of the three branches are calculated according to the positive sequence current component of the double-circuit T-type power transmission line, and a fault branch can be determined according to difference of the distance measurement functions of two ends of each branch; and lastly, a fault distance analysis expression is utilized to calculate a fault distance on a fault branch.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a fault location method for double-circuit T-type transmission lines on the same tower based on positive sequence current difference. Background technique [0002] With the continuous development of the power system, T-shaped branch lines appear more and more in the high-voltage power grid. Double-circuit lines paralleled on the same tower are increasingly widely used in high-voltage transmission and distribution networks due to their advantages such as large transmission capacity, narrow outlet corridor, and small footprint. The double-circuit lines on the same tower are connected to each other to form a double-circuit T-shaped transmission line. The double-circuit T-shaped line has a heavy transmission load. Once a fault occurs, it is urgent to locate it accurately and quickly troubleshoot the fault. Due to the particularity of the T-shaped line...

AI Technical Summary

Problems solved by technology

At present, the existing T-type line fault analysis methods are mostly for single-circuit lines. The problems of these methods are: when a high-impedance short circuit occurs near the T node, there is a dead zone in the identification of the fault branch, and the distance measurement results are affected by the nature of the transition resistance. It is necessary to search and find fault points on the whole line of each branch, and the numerical solution of the distance measurement equation has convergence and pseudo-root problems.

Compared with single-circuit lines, the structure of double-circuit lines paralleled on the same tower is more complex. There are coupling effects between double-circuit lines and various types of faults, which increases the difficulty of fault location for double-circuit T-shaped transmission lines, and there are relatively few related studies.

Most of the fault location methods for double-circuit T-shaped lines that have been proposed are derived by using centralized parameter line models, which cannot be applied to long-distance high-voltage transmission lines with large ground-distributed capacitance.

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